Hydrogels are flexible materials characterized by a 3D network structure, which possess high water content and adjustable physicochemical properties. They have found widespread applications in tissue engineering, electronic skin, drug delivery, flexible sensors, and photothermal therapy. However, hydrogel networks often exhibit swelling behavior in aqueous environments, which can result in structural degradation and a loss of gel performance. In this study, polyacrylic acid is utilized as the primary network structure with the incorporation of the natural polymer chitosan. Furthermore, a conductive hydrogel exhibiting good mechanical strength similar to human skin and excellent anti-swelling properties is developed by integrating phytic acid into the hydrogel network. The as-prepared hydrogels exhibited maximum swelling in pure water, achieving an equilibrium swelling rate of 15%. Additionally, a dopamine-grafted polyacrylic acid binder is synthesized through a coupling reaction to enhance the adhesion of the hydrogels to various substrates. The hydrogels demonstrated strong adhesion properties with different substrates. Whether in the air or underwater, the hydrogel sensor effectively monitors human movement behaviors. Furthermore, by utilizing the sensing signals to send Morse code, the hydrogel sensor can facilitate underwater communication. This type of hydrogel sensor is anticipated to play a significant role in wearable sensing applications and underwater communication.